In general, 5-HT4 receptor agonists are found to be useful for the treatment of a variety of diseases such as gastroesophageal reflux disease, gastrointestinal disease, gastric motility disorder, non-ulcer dyspepsia, functional dyspepsia, irritable bowel syndrome (IBS), constipation, dyspepsia, esophagitis, gastroesophageral disease, nausea, central nervous system disease, Alzheimer's disease, cognitive disorder, emesis, migraine, neurological disease, pain, cardiovascular disorders, cardiac failure, heart arrhythmia, diabetes and apnea syndrome (See TiPs, 1992, 13, 141; Ford A. P. D. W. et al., Med. Res. Rev., 1993, 13, 633; Gullikson G. W. et al., Drug Dev. Res., 1992, 26, 405; Richard M. Eglen et al, TiPS, 1995, 16, 391; Bockaert J. Et al., CNS Drugs, 1, 6; Romanelli M. N. et al., Arzheim Forsch./Drug Res., 1993, 43, 913; Kaumann A. et al., Naunyn-Schmiedeberg's. 1991, 344, 150; and Romanelli M. N. et al., Arzheim Forsch./Drug Res., 1993, 43, 913). Also, Mosapride is known to be useful for the treatment of diabetes.
It would be desirable if there were provided 5-HT4 receptor agonists which have more 5HT4 receptor agonistic activities.
U.S. Pat. No. 5,223,511 discloses benzimidazole compounds as 5-HT4 receptor antagonists. Especially, compounds represented by the following formula is disclosed:

WO93/18027 discloses benzimidazolone compounds as 5-HT4 receptor antagonists. Especially, compounds represented by the following formula is disclosed:

WO99/17772 discloses benzimidazolone compounds as 5-HT4 receptor agonists and/or antagonists. Especially, compounds represented by the following formula is disclosed:

WO94/00449 discloses benzimidazolone compounds as 5-HT4 agonists or antagonists and/or 5-HT3 antagonists. Especially, compounds represented by the following formula is disclosed:

There is a need to provide new 5-HT4 agonists that are good drug candidates. In particular, preferred compounds should bind potently to the 5-HT4 receptor whilst showing little affinity for other receptors and show functional activity as agonists. They should be well absorbed from the gastrointestinal tract, be metabolically stable and possess favorable pharmacokinetic properties. When targeted against receptors in the central nervous system they should cross the blood brain barrier freely and when targeted selectively against receptors in the peripheral nervous system they should not cross the blood brain barrier. They should be non-toxic and demonstrate few side-effects. Furthermore, the ideal drug candidate will exist in a physical form that is stable, non-hygroscopic and easily formulated.